G. ISIS. 
233 
Their height varies from one to four decimetres. 
They originate in the Indian and Australasian seas. 
VERTICILLATED. 
1. Mopsea verticillata. Branches pinnated ; twigs 
simple, and long ; polypi recurved like a hook.— 
Plate 18. fig. 2. 
Australasia. 
DICHOTOMOUS. 
2. Mopsea dichotoma. Branches slender, cylin- 
drical, almost filiform, and dichotomous at each arti- 
culation ; polypi mammiform in the higher branches, 
tuberculous in the middle ones, and superficial in the 
lower; rind smooth upon the stem, 
Indian Ocean. 
ISIS. 
A tree-formed Polypidom ; rind very thick, 
friable, not adhering to the axe, from which it easily 
detaches ; cells dispersed and superficial. 
The Isideas, like all the corticiferous Polypidoms, 
are composed of two parts, one central, called the axe, 
and an envelope of a fleshy consistency, called the 
rind, as in the Gorgonias. In this genus, however, 
the articulations which mark the order are alter- 
nately stony and horny, varying in their height and 
their diameter: the first are white, slightly trans- 
lucent, marked with longitudinal furrows of greater 
or less depth, sometimes larger and frequently 
Cor. 2 
G 
